Abstract

Management of the perioperative period plays an important role in reducing anaesthetic-related mortality in cats and dogs. This chapter describes the scientific facts of perioperative risk revealed by one major study that investigated small animal anaesthetic fatalities and discusses anaesthetic risk factors in dogs and cats, proper patient positioning, body temperature and its regulation, recovery and handover from theatre team to postoperative team.

3.1(a) Poor positioning of a cat for laparotomy. The limbs are over-extended and the tension on the thorax impairs thoracic movements. The pelvic limbs are pulled below the level of the heart. (b) The same cat after repositioning to a better position. Sandbags underneath the heating blanket are used to keep the cat in stable dorsal recumbency. The limbs are in a relaxed position and higher than the heart to avoid pooling of blood in the limbs.

3.2Heat distribution in the dog. (a) In the awake dog, the core compartment varies little in temperature. The peripheral compartment absorbs or releases heat to maintain normothermia. The temperature in the peripheral compartment can vary by up to 8°C. (b) Internal redistribution of body heat following induction of general anaesthesia (phase 1). Heat is redistributed into the peripheral compartment through vasodilation, leading to a drop in core temperature.

3.3Typical curve for the development of hypothermia during general anaesthesia. The initial decrease (phase 1) results from a redistribution of body heat from the core to the periphery. This is followed by phase 2, in which a further decrease in temperature results from heat loss exceeding heat production. Finally, a plateau is reached where heat production equals heat loss (phase 3).

3.5Dog anaesthetized for treatment of a burn wound caused at an earlier stage by an electrical heating mat placed beneath the dog during ovariohysterectomy in dorsal recumbency. (Courtesy of Stephanie Picek, University of Zürich)

3.6Cat under general anaesthesia. The blanket of an electrical heating system (Hot Dog® device) is wrapped around the patient to minimize heat loss. (Courtesy of Charlotte Marly-Voquer, University of Zürich)

3.8Recovery set-up for a cat with postoperative shivering. A forced warm air system and a heat lamp are used to rewarm the patient. Oxygen is being delivered via facemask to compensate for the increase in oxygen demand due to the shivering.